Title

Gene Expression of a Two-Component Regulatory System Associated with Sunscreen Biosynthesis in the Cyanobacterium Nostoc Punctiforme ATCC 29133

Document Type

Article

Publication Date

Spring 2016

Publication Source

FEMS Microbiology Letters

Volume

363

Issue

2

Inclusive pages

fnv235

DOI

10.1093/femsle/fnv235

Peer Reviewed

yes

Abstract

Long-wavelength ultraviolet radiation (UVA) can damage cells through photo-oxidative stress, leading to harmful photosensitized proteins and pigments in cyanobacteria. To mitigate damage, some cyanobacteria secrete the UVA-absorbing pigment scytonemin into their extracellular sheath. Comparative genomic analyses suggest scytonemin biosynthesis is regulated by the two-component regulatory system (TCRS) proteins encoded by Npun_F1277 and Npun_F1278 in the cyanobacterium Nostoc punctiforme ATCC 29133. To understand the dynamics of these genes, their expression was measured following exposure to UVA, UVB, high visible (VIS) irradiance, and oxidative stress for 20, 40, and 60 min. Overall, both genes had statistically similar patterns of expression for all four conditions and were generally up-regulated, except for those exposed to UVB by 60 min and for the cells under oxidative stress. The greatest UVA response was an up-regulation by 20 min, while the response to UVB was the most dramatic and persisted through 40 min. High VIS irradiance resulted in a modest up-regulation, while oxidative stress caused a slight down-regulation. Both genes were also found to occur on the same transcript. These results demonstrate that these genes are positively responding to several light-associated conditions, which suggests that this TCRS may regulate more than just scytonemin biosynthesis under UVA stress.

Keywords

cyanobacteria, two-component regulatory system, ultraviolet stress, gene expression, Nostoc, scytonemin

Disciplines

Biology | Microbiology

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